Conventional drum brake systems, such as used on trucks and tractor-trailer rigs, are difficult and time-consuming to work on. Accordingly, vital maintenance of the braking system is often deferred, which deferral of needed work can lead to diminished braking capacity, increased wear on the components, and the like. One reason maintenance is often deferred on conventional braking systems is that the large amount of time required for servicing the system results in undesirable and uneconomic down time of the vehicle on which the system is placed.
In addition, many conventional braking systems require replacement of bearings, seals and/or lubricants, such as when conventional brake linings are replaced. Such replacement of bearings and seals is expensive, and time consuming. The loss of lubricants, which often occurs at an off-site location when brake repairs are necessary in the field, is not only an added expense, but is also environmentally unfriendly.
Many attempts have been made to provided braking systems having easily replaced components.
U.S. Pat. No. 5,119,909 to Shim discloses a brake shoe construction having ears interfingered with a pad. Shim states that the pad can be readily removed and replaced without removing the brake pad and the shoe. Shim contemplates an optional raised ridge 130 formed on Shim pad 46 with its mating complementary groove 132 in flange 38 of shoe 20. Although Shim discloses a lug 82 which mates with recesses 86 in the embodiment of FIG. 9, Shim failed to eliminate the use of fasteners, such as a screw 56 for securing the ends of the Shim pad against any movement with respect to Shim flange 38, as shown in Shim's embodiment of FIGS. 6-9, for example.
U.S. Pat. No. 2,229,922 to Heinze discloses a shoe having dovetail sections (FIG. 5) for mating with dovetail slots of Heinze blocks (FIG. 4).
U.S. Pat. No. 4,429,770 to Weisbrod is of interest for its disclosure of a friction lining carrier member having replaceable friction linings which have angled faces.
Both the Heinze and Weisbrod patents described immediately above are apparently time-consuming to use, and lack the simplicity of the present invention.
U.S. Pat. No. 2,647,592 to Tilden discloses generally the configuration of a brake lining segment being substantially aligned with a counterpart free edge of a brake drum.
U.S. Pat. No. 3,367,458 to Self is of general interest for its disclosure of removing brake shoes without jacking the vehicle axle and without breaking the seals, as in most other conventional brake shoe assemblies.